A big question is whether these areas actually turn into denser housing, or whether something else in the process manages to bog it down. Plenty of housing bills have seemed like a big deal when you looked at the area they impacted, but in practice they led to little new housing.

A lot of the California bills had various poison pills in them that reduced their effectiveness.

For example, SB684 allowed building and subdividing up to 10 units on a multifamily lot. BUT, the lot wasn’t eligible if you had to knock down a building that had tenants in the past N years to avoid displacement of people.

You can probably guess how many multifamily lots are out there where you don’t have to tear down an existing building with tenants.

There are other issues too. Interest rates and tariffs make a lot of projects not viable financially.

The problem we are seeing in suburban MA right now is that they're building the wrong kind of housing to address the greatest shortage, and doing it in a way that does not promote the long-term community well-being. Developers are jamming in large numbers of small "luxury" units with insufficient parking in a car-dependent area in whatever lot they can get their hands on, instead of density increasing organically throughout the immediate area around downtown, adding ADUs and replacing large single family homes with 2/3/4-unit condos.

Why is this happening? Because zoning boards don't allow reasonable multifamily development in densifying areas, so developers do the only thing they can do, which is build in already-built-up areas with looser zoning, and/or ram projects through using a state low income housing provision called 40B.

The effect is that while the apartment market for young professionals is going to continue to soften, the market for comfortable family dwellings remains brutal and increasingly unaffordable. There are 80+ unit apartment buildings literally surrounded by multi-lane stroads, while less than a mile away there are single family homes on quiet tree lined streets where you could easily have the same number of units in multifamily condo buildings and garden apartments, and still retain the comforts of suburbia.

So whatever poison pills are in here, it cannot be worse than the status quo in MA, in which the development is too much of the wrong thing and everyone loses in the end except the developers and real estate agents.

Yes, sadly just because the zoning has changed does not mean that any of the buildings that already exist will be torn down and rebuilt for decades, if not longer. And localities have all kinds of restrictions and fees that still prevent building to take place.